Charging the battery of a motor vehicle requires a current that is typically equal to 14 amps (A) to pass through the battery for several hours.
For practical reasons, it is thus advantageous for the user to plug the battery of the motor vehicle into a standard domestic socket outlet that is standardized for 16 A.
Theoretically, that type of socket outlet presents intrinsic characteristics that enable it to deliver a current that is less than or equal to 16 A for a standardized duration.
However, that type of socket outlet satisfies standard requirements that are defined for ordinary domestic uses for which the current delivered is usually less than 14 A or 16 A, with the socket outlet being used at frequencies and for durations that are less than the frequencies and the durations that are necessary for charging the battery of a motor vehicle.
Furthermore, in practice, the intrinsic characteristics of the socket outlets installed in the homes of users may vary from one socket outlet to another, and may also vary over time. It is impossible to know such characteristics with certainty.
It is also possible that the user is confronted with a socket outlet that does not comply with the standard.
Such uncertainty concerning the intrinsic characteristics of socket outlets, and thus concerning suitability for delivering a current of 14 A or more for several hours, and in regular manner, is not acceptable since it jeopardizes the safety of people and of installations.
A novel domestic application such as charging an electric vehicle may stress socket outlets to the limits of standard characteristics, and consequently requires accurate knowledge of the type and of the quality of the socket outlet used in order to take advantage of the maximum capacities of the socket outlet without damaging it.
Unfortunately, presently known electric plugs that are connected to electrical equipment are not arranged to recognize the characteristics of a socket outlet into which they are plugged.
An electrical appliance connected to a standard electric plug draws a current that is determined by its own characteristics, without it being possible for the appliance to adapt its operation to the socket outlet into which it is plugged.
By way of example, document DE102009030092 discloses an electrical assembly comprising a socket outlet and an electric plug that is adapted to be inserted into the socket outlet. The electric plug includes connection recognition means that are adapted to receive a connection signal issued by the socket outlet, and communication means that are adapted to receive identification data from the socket outlet and to issue a validation signal if the data is satisfactory.
However, a drawback of that assembly is that it does not have any means for detecting a spurious signal that does not originate from one of its elements, i.e. from the plug or from the socket outlet.